You are Here: Home >< Maths

Announcements Posted on
Would YOU be put off a uni with a high crime rate? First 50 to have their say get a £5 Amazon voucher! 27-10-2016
1. The quadratic equation x^2+ 2kx + 2(k + 4) = 0 has distinct real roots. Show that k^2 – 2k – 8 > 0.
2. (Original post by kitkat132000)
The quadratic equation x^2+ 2kx + 2(k + 4) = 0 has distinct real roots. Show that k^2 – 2k – 8 > 0.
The discriminant is greater than 0 for 2 distinct roots.
• By applying the discriminant, b^2-4ac...
• (2k)^2-4(1)(2k+8)>0
• Can you do the rest?
3. (Original post by AlexOD)
Full Solution
Yeah easy-peasy but full solutions are not allowed on this forum.
4. Oh sorry I didn't know that...
5. Ok thanks! So is the answer 34>0 which proves that the quadratic is greater than 0.
6. (Original post by kitkat132000)
Ok thanks! So is the answer 34>0 which proves that the quadratic is greater than 0.
If you're given a particular value of k to test and it turns out to be 34 on the LHS, then yes. If not, then you simply need to arrive at the required answer without doing anything else. Just saying this as I do not know where you pulled the 34 from.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: October 11, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

Find out here

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams